Integral add heat and surge control valve for compressor

ABSTRACT

A compressed air system includes a compressor having an inlet and an outlet. A duct fluidly connects the outlet to the inlet and has a valve arranged in the duct. A controller communicates with the valve and commands the valve to move between first and second positions in response to a surge condition and/or an add-heat condition to regulate an amount of fluid flowing through the duct. The valve opens to provide hot air from the compressor outlet to deice the inlet or to provide the higher pressure compressor outlet air to the lower pressure compressor inlet air to obtain a pressure ratio in a desired range. The inventive compressed air unit is designed to provide a compact arrangement so that the valve providing the heated, pressurized air to the inlet is located in close proximity to the inlet for a rapid response time. The duct comprises a relatively short length of tubing interconnecting an add-heat supply outlet and an add-heat plenum inlet, which are provided by a housing of the compressor. The housing also includes an add-heat plenum having an annular wall arranged at the inlet to provide an annular cavity. Hot air from the compressor outlet is provided to the plenum to heat the annular wall quickly at the inlet to prevent deicing.

The present application is a continuation-in-part application of U.S. application Ser. No. 10/978,641 filed on Nov. 1, 2004 that claims priority to U.S. Provisional Patent Application Ser. No. 60/611,992, filed Sep. 22, 2004.

BACKGROUND OF THE INVENTION

This invention relates to a compressor that is used, for example, in an aircraft for supplying compressed air to a cabin air conditioning system.

In some compressor applications in aircraft, air entering a compressor inlet contains water and operates at temperatures below freezing. Ice forming at the inlet reduces the thermodynamic performance of the compressor, can cause damage to the compressor as the ice sheds and can damage the bearing and support structure of the compressor.

Compressors may occasionally operate in an undesirable surge condition in which the ratio between compressor outlet and compressor inlet pressures is undesirable. To avoid surge it is desirable to either lower the compressor outlet pressure or raise the compressor inlet pressure to obtain a pressure ratio within a desired range.

What is needed is a deicing and surge control device that is capable of deicing the compressor inlet and controlling surge in efficient, rapid manner.

SUMMARY OF THE INVENTION

The invention provides a compressed air system that includes a compressor having an inlet and an outlet. A duct fluidly connects the outlet to the inlet and has a valve arranged in the duct. A controller communicates with the valve and commands the valve to move between first and second positions in response to a surge condition and/or for an add-heat condition to regulate an amount of fluid flowing through the duct. The valve opens to provide hot air from the compressor outlet to deice the inlet or to provide the higher pressure compressor outlet air to the lower pressure compressor inlet air to obtain a pressure ratio in a desired range.

The inventive compressed air unit is designed to provide a compact arrangement so that the valve providing the heated, pressurized air to the inlet is located in close proximity to the inlet for a rapid response time. The duct comprises a relatively short length of tubing interconnecting an add-heat supply outlet and an add-heat plenum inlet, which are provided by a housing of the compressor. The housing also includes an add-heat plenum having an annular wall arranged at the inlet to provide an annular cavity. Hot air from the compressor outlet is provided to the plenum to heat the annular wall quickly at the inlet to prevent deicing.

Accordingly, the present invention provides a deicing and surge control device that deices the compressor and prevents surge.

These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of the inventive compressed air system.

FIG. 2 is a perspective view of an inventive compressed air unit having a combined electric motor and compressor with integrated add heat and surge control features.

FIG. 3 is a cross-sectional view of the inventive compressed air unit shown in FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A compressed air system is shown schematically at 10 in FIG. 1. The compressed air system 10 includes a compressed air unit 12 comprising a compressor 14 driven by an electric motor 16. A diffuser 18 is arranged before an outlet 22 of the compressor 14, as is known in the art. The diffuser 18 is manipulated by an actuator 19 to vary its area. Air enters the compressor 14 through an inlet 20. Pressure and temperature inlet sensors 24 and 26 are arranged at the inlet 20, and a pressure outlet sensor 28 is arranged at the outlet 22. The actuator 19 and sensors 24, 26 and 28 are schematically shown in communication with a controller 34. The controller 34 uses the sensors 24, 26 and 28 to determine surge and add-heat conditions. The compressed air system 10 described above is suitable for providing, for example, compressed air to an air cycle machine for producing conditioned cabin air.

The present invention utilizes a duct 30 to fluidly connect the inlet 20 and outlet 22. A valve 32 is arranged between the inlet 20 and outlet 22 within the duct 30. The controller 34 is in communication with the valve 32 to move it between first and second positions F and S in response to the surge and add-heat conditions. According to this invention, only one valve is used for these conditions. In one example, the valve 32 is a butterfly valve.

Referring to FIGS. 2 and 3, wires 36 extend from a housing 40 to provide power to the electric motor 16. The housing 40 includes motor, outlet, add-heat and inlet housing portions 42, 44, 46 and 48 secured to one another by fasteners 49. A screen 50 is arranged between the add-heat housing 46 and the inlet housing 48. A cooling supply plenum 52 is arranged at the inlet 20 to provide cooling air for the electric motor 16. The cooling supply plenum 52 is defined, in part, by first and second flanges 51 and 53. The cooling supply plenum 52 includes an outlet 54 that is connected to a cooling inlet 56 by a bearing cooling duct 38 (shown in FIG. 2). Bearings 62 support a rotor 64 of the electric motor 16. A bearing cooling inlet 58 provides cooling air to a bearing cooling outlet 60 via a duct (not shown).

An impeller 66 is secured to the rotor 64. The impeller 66 has an inlet side 65 and outlet side 67. The diffuser 18 is arranged on the outlet side 67 between the impeller 66 and the outlet 22. The housing 40 includes a diffuser shroud 68 in close proximity to the impeller 66. The diffuser shroud 68 extends beyond an end 69 of the impeller 66.

The housing 40 provides an add-heat plenum 72 formed by the diffuser shroud 68 and the add-heat housing 46. The diffuser shroud 68 provides a curved annular wall 70 that tapers radially outwardly as it extends axially away from the end 69 of the impeller 66.

The outlet housing 44 provides an add-heat supply outlet 74 (best shown in FIG. 2) that is connected to an add-heat plenum inlet 76 of the add-heat housing 46. In the example shown, the duct 30 is relatively short having a length L2 (represented by the dashed line) that is less than a length L1 of the compressed air unit 12. This relatively short length enables the curved annular wall 70 to be quickly heated in response to sensing an add-heat condition. Similarly, the response time when sensing a surge condition is rapid. A remotely located valve may not provide a desirable response time.

Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention. 

1. A compressed air system comprising: a compressor having an inlet and an outlet; a duct fluidly connecting the outlet to the inlet with a valve arranged in the duct; and a controller communicating with the valve and commanding the valve to move between first and second positions in response to a surge condition and an add-heat condition to regulate an amount of fluid flowing through the duct.
 2. The system according to claim 1, comprising inlet and outlet pressure sensors respectively associated with the inlet and outlet, the controller monitoring a ratio of inlet and outlet pressures respectively from the inlet and outlet pressure sensors to determine the surge condition.
 3. The system according to claim 1, comprising an inlet temperature sensor associated with the inlet, the controller monitoring an inlet temperature from the inlet temperature sensor to determine the add-heat condition.
 4. The system according to claim 1, wherein the compressor includes a housing providing an add-heat plenum having a generally annular wall, the add-heat duct fluidly connecting the add-heat plenum to the outlet.
 5. The system according to claim 4, wherein the housing includes a shroud at least partially surrounding an impeller of the compressor, the shroud providing the generally annular wall.
 6. The system according to claim 4, wherein the valve is moved from the first position to the second position in response to the add-heat condition providing fluid from the outlet to the add-heat plenum to heat the annular wall.
 7. A compressed air unit comprising: a housing including first and second housing portions respectively providing an inlet and an outlet, and the first and second housing portions respectively providing an add-heat plenum inlet and an add-heat supply outlet respectively in fluid communication with the inlet and outlet; an impeller arranged in the housing between the inlet and the outlet for compressing fluid; and a duct fluidly connecting the add-heat supply outlet and the add-heat plenum inlet with a valve arranged in the duct for regulating the flow of fluid from the outlet to the inlet.
 8. The unit according to claim 7, wherein the first housing is an outlet housing and the second housing is an add-heat housing secured to the outlet housing, the housing including an inlet housing secured to the add-heat housing opposite the outlet housing, the add-heat and inlet housings arranged upstream of the impeller.
 9. The unit according to claim 8, wherein a shroud is arranged between the impeller and the add-heat housing forming an add-heat plenum in fluid communication with the add-heat plenum inlet, the shroud providing an annular wall.
 10. The unit according to claim 8, wherein the housing includes a motor housing secured to the outlet housing opposite the add-heat housing, an electric motor arranged in the motor housing and including a rotor coupled to the impeller.
 11. The unit according to claim 7, wherein the housing has a length that is greater than a length of the duct.
 12. The unit according to claim 7, wherein a variable diffuser is arranged between the impeller and the outlet.
 13. A compressed air unit comprising: a housing including an inlet and an outlet; an impeller arranged between the inlet and outlet; and a portion of the housing providing a plenum including an annular wall defining an annular cavity, the annular cavity in fluid communication with the inlet and the outlet, and the annular wall near the impeller.
 14. The unit according to claim 13, wherein a duct fluidly connects the outlet and the plenum, and a valve arranged in the duct.
 15. The unit according to claim 13, wherein the impeller includes an end and the annular wall extends across the end and away from the impeller.
 16. The unit according to claim 13, wherein the annular wall tapers radially outwardly in a direction axially away from the impeller. 